Deck 5: Volcanoes and Volcanic Eruptions

Question 1

Which of the following is an indirect or secondary hazard associated with a volcanic eruption?

A) ash fall
B) pyroclastic flow
C) lahar
D) lateral blast
E) poisonous gases

Answer 1

C

Question 2

Which of the following volcanic products is most hazardous to air traffic?

A) pyroclastic flows
B) volcanic ash
C) lahars
D) volcanic bombs
E) lava flows

Answer 2

B

Question 3

Jokulhlaups are

A) floods induced by volcanic eruptions underneath glaciers.
B) rubbly, slow moving lava flows in Iceland, similar to aa in Hawaii.
C) plants that tolerate highly acidic soils that are the first to recolonize a lava flow.
D) low viscosity basaltic lava flows at hotspots like Iceland.
E) tsunami-triggering collapses of basaltic rock off of Iceland.

Answer 3

A

Question 4

Which magma composition will produce the most explosive volcanoes?

A) basalt
B) andesite
C) dacite
D) rhyolite
E) gabbro

Question 5

The two primary volcanic gases are

A) hydrogen sulfide and carbon monoxide.
B) carbon monoxide and carbon dioxide.
C) chlorine gas and carbon monoxide.
D) carbon dioxide and water vapour.
E) chlorine gas and hydrogen sulfide.

Question 6

How can studying the geologic history of a volcano help most in eruption forecasting?

A) Most volcanoes erupt with a regular periodicity, so knowing the time period between eruptive cycles allows accurate predictions of when the next eruption will occur.
B) Information from geologic records allows scientists to pinpoint how big the next eruption will be from a certain volcano.
C) Mapping previous volcanic deposits from a volcano is helpful for developing hazard maps for use in land-use planning and disaster preparedness.
D) Mapping pyroclastic flows from previous eruptions will show exactly where the pyroclastic flows will go in the next eruption.
E) Mapping the extent of lahars from previous eruptions will show exactly where the lahars will go in the next eruption.

Question 7

Which of the following is the most common volcanic rock on Earth?

A) basalt
B) andesite
C) dacite
D) rhyolite
E) granite

Question 8

Which type of volcano is most common around the Pacific Rim?

A) shield volcano
B) stratovolcano
C) caldera
D) cinder cone
E) volcanic dome

Question 9

Which of the following eruptions had the highest Volcanic Explosivity Index?

A) Mount St. Helens, 1980
B) Mt. Pinatubo, 1991
C) Kilauea, 2007
D) Yellowstone caldera, 600,000 years ago
E) Mt. Unzen, 1991

Question 10

What is the composition of volcanic material erupted from cinder cones?

A) basalt
B) andesite
C) dacite
D) rhyolite
E) granite

Question 11

Basic names of volcanic rocks are based on the rock's

A) iron content.
B) magnesium content.
C) aluminum content.
D) silica content.
E) calcium content.

Question 12

Which type of volcano has very gentle slopes?

A) composite volcano
B) stratovolcano
C) volcanic dome
D) cinder cone
E) shield volcano

Question 13

Maars are

A) lava flows on Earth's Moon.
B) cinder cones on the flanks of larger volcanoes.
C) lava flows in Hawaii that flow all the way to the ocean and are quenched by seawater.
D) craters formed by the interaction of magma with groundwater.
E) basaltic lava flows with low explosivity.

Question 14

A group of volcanoes in central British Columbia extends from west to east,growing progressively older to the west.The youngest volcano (at the east end)is about 8 thousand years old.This age progression implies that movement of the North American Plate in this region has been to the

A) west.
B) east.
C) northwest.
D) northeast.
E) southwest.

Question 15

Immediately after an eruption at Kilauea in Hawaii,the surface of the volcano

A) inflates, making the slopes of the volcano slightly steeper.
B) subsides, making the slopes of the volcano less steep.
C) shows higher tilt in the north-south direction.
D) shows higher tilt in the east-west direction.
E) cracks open in many places surrounding the summit.

Question 16

How did the residents of Vestmannaeyjar,Iceland,save their harbor from a lava flow?

A) They dug channels that diverted the lava flow away from the harbor.
B) They extracted more geothermal energy that was being produced by the volcano, decreasing the volume of lava erupted.
C) They constructed high cement walls around the harbor and the lava solidified against the walls.
D) As the lava cooled, they blasted the new rock away and dumped it offshore.
E) They chilled the lava flow with water, making the flow solidify before it blocked the harbor.

Question 17

Large eruptions from stratovolcanoes typically affect climate by

A) heating the atmosphere, causing global warming.
B) SO₂ and ash particles blocking sunlight and causing global cooling.
C) melting large quantities of ice causing sea level to rise.
D) heating ocean water with lava flows.
E) reducing alpine ice cover, contributing to global warming.

Question 18

Which of the following volcanic hazards has been deadliest for people?

A) lava flows
B) ash falls
C) lahars
D) volcanic bombs
E) pyroclastic flows

Question 19

Which volcano poses the greatest risk to southern British Columbia?

A) Mt. Garibaldi
B) Mt. Meager
C) Mt. Cayley
D) Mt. Baker
E) Mt. Rainier

Question 20

Which of the following volcanic hazards can occur without an accompanying eruption?

A) lava flow
B) pyroclastic flow
C) sector collapse
D) volcanic bombs
E) volcanic ash cloud

Question 21

The most lethal volcanic phenomena (responsible for the most deaths)are

A) lava flows.
B) lahars.
C) pyroclastic flows.
D) ash falls.
E) poisonous gasses.

Question 22

The interaction between magma and groundwater produces steam that causes which kind of eruptions?

A) Stratovolcanoes
B) Maars
C) Cinder cones
D) Volcanic domes
E) Shield volcanoes

Question 23

Approximately how many people live in close proximity to active volcanoes?

A) 1 million
B) 5 million
C) 50 million
D) 500 million
E) 1 billion

Question 24

Which of the following is a stratovolcano in British Columbia?

A) Mount Baker
B) Mauna Loa
C) Mount Vesuvius
D) Mount Garibaldi
E) Tambora

Question 25

What kind of magma is dominantly produced at spreading ridges?

A) rhyolite
B) basalt
C) dacite
D) andesite
E) tephra

Question 26

What feature is caused by the collapse of the roof of an empty magma chamber?

A) a volcanic tube
B) a maar
C) a geyser
D) a caldera
E) hot springs

Question 27

Which of the following is usually the first sign of impending eruption of a volcano?

A) small earthquakes
B) increased hot spring activity
C) changes in gas emissions
D) changes in slope of the volcano
E) changes in magnetic properties of the volcano

Question 28

Basaltic eruptions

A) tend to have low viscosity.
B) produce stratovolcanoes.
C) occur at subduction zones.
D) are associated with strike-slip faults.
E) produce abundant tephra.

Question 29

What process causes melting of rocks in subduction zones?

A) decompression of the mantle
B) addition of heat from the subducting plate
C) addition of water into the mantle from the subducting slab
D) removal of water from the mantle
E) convection of the asthenosphere

Question 30

Dacitic and andesitic eruptions

A) are commonly explosive.
B) build shield volcanoes.
C) erupt frequently and quietly.
D) have low gas contents.
E) produce little tephra.

Question 31

Which of the following is a classic example of a shield volcano?

A) Mount Baker, Washington
B) Mauna Loa, Hawaii
C) Mount Fuji, Japan
D) Mount Vesuvius, Italy
E) Mount St. Helens, Washington

Question 32

Volcanic debris flows commonly caused by melting ice on the flanks of a volcano are called

A) maars.
B) lahars.
C) jokulhlaups.
D) pyroclastic surges.
E) pyroclastic flows.

Question 33

Which of the following is a volcano in Canada that has undergone post-glacial eruption?

A) Mount Garibaldi
B) Mount Baker
C) Mount St. Helens
D) Mount Meager
E) None of the above; there are no post-glacial volcanoes in Canada.

Question 34

Eruption under glacial ice produces outbursts of water from the glacier called

A) jokulhlaups.
B) maars.
C) tuyas.
D) pillow basalts.
E) pyroclastic flows.

Question 35

Basaltic lavas

A) are very hot.
B) result from melting of the mantle.
C) are rich in iron and magnesium.
D) have low viscosity.
E) all of the above.

Question 36

Which of the following is considered a secondary effect of volcanic eruption?

A) pyroclastic flow
B) lahar
C) pyroclastic surge
D) poisonous gas
E) ash fall

Question 37

Mount Vesuvius overlooks which modern Italian city?

A) Rome
B) Milan
C) Venice
D) Naples
E) Turin

Question 38

Lava that solidifies with a smooth ropy surface is called

A) aa.
B) pahoehoe.
C) tephra.
D) dacite.
E) pyroclastic.

Question 39

In 1986,Lake Nyos,a crater lake in the Cameroon highlands West Africa,erupted a cloud of which gas that killed over 1700 people.

A) chlorine
B) carbon monoxide
C) sulphur dioxide
D) carbon dioxide
E) hydrogen sulphide

Question 40

Which of the following is probably the most common secondary effect of volcanic eruptions?

A) tsunami
B) landslides
C) forest fires
D) flooding
E) climatic change

Question 41

Which of the following lava compositions would have the highest viscosity?

A) basalt
B) rhyolite
C) dacite
D) andesite
E) rhyodacite

Question 42

Most active volcanoes are located near plate tectonic boundaries.

Question 43

Which of the following is a secondary effect of a volcanic eruption?

A) pyroclastic flows
B) ash falls
C) lava flows
D) poisonous gas emissions
E) lahars

Question 44

The presence of water lowers the melting temperature of rocks.

Question 45

Dacite has a higher silica content than basalt does.

Question 46

Shield volcanoes are largely the products of this type of eruption.

A) explosive
B) dacite lavas
C) rhyolite lavas
D) basaltic magmas
E) andesitic melts

Question 47

Sulphur dioxide from volcanoes can combine with water vapour in the atmosphere and produce acid rain.

Question 48

The most abundant elements in magma are

A) nickel and iron.
B) silicon and calcium.
C) iron and magnesium.
D) iron and silicon.
E) silicon and oxygen.

Question 49

The Nevado del Ruiz Volcanic disaster,which killed over 23,000 people,was due largely to this type of secondary effect.

A) poisonous gas
B) landslide
C) fire
D) tsunami
E) lahar

Question 50

Which of the following is NOT a natural service function of volcanoes?

A) geothermal power
B) fertile volcanic soils
C) recreation
D) release of gases
E) creation of new land

Question 51

hotspots form volcanoes only in the ocean.

Question 52

Lava from stratovolcanoes typically flows much farther than lava from shield volcanoes.

Question 53

Lapilli are larger than volcanic bombs.

Question 54

Eruptions at mid-ocean ridges are highly explosive.

Question 55

The largest volcanoes on the planet are

A) shield volcanoes.
B) volcanic domes.
C) composite volcanoes.
D) stratovolcanoes.
E) cinder cones.

Question 56

Magmas with high silica content tend to have lower temperatures.

Question 57

The viscosity of magma or lava is largely based on its ________ content.

A) sodium
B) silica
C) calcium
D) magnesium
E) iron

Question 58

Caldera-forming eruptions are the largest and most deadly types of eruptions.

Question 59

Magmas with low silica content tend to have higher viscosity.

Question 60

Of the following volcanic eruptions,which is considered to be the deadliest?

A) Vesuvius, Italy - A.D. 79
B) Krakatoa, Indonesia - 1883
C) Mount St. Helens, United States - 1980
D) Mount Pinatubo, Philippines - 1991
E) Eyjafjallajokull, Iceland - 2010

Question 61

Stratovolcanoes form at divergent plate margins.

Question 62

Mid-ocean ridge volcanism results from melting asthenosphere.

Question 63

Lava cooled rapidly by water or ice forms "pillows."

Question 64

A landslide or sector collapse led to the eruption of Mount St.Helens.

Question 65

Silica-rich magmas are noted for their high viscosity,which results in slow moving lava flows and highly explosive eruptions.

Question 66

All active volcanoes on land are located along the Ring of Fire.

Question 67

The eruption of Mount St.Helens was triggered by an earthquake and landslide.

Question 68

Stratovolcanoes have been responsible for most of the volcano-related deaths.

Question 69

Volcanoes occur on all seven continents as well as the ocean floor.

Question 70

The eruption of Mount St.Helens was an example of a super eruption.

Question 71

Basaltic magma can change composition slowly over time.

Question 72

Calderas produce flood basalts.

Question 73

Some suburbs of Seattle,Washington are built on ancient mudflow deposits from Mt.Rainier.

Question 74

The Ring of Fire includes most of the world's onshore volcanoes.

Question 75

Weathering volcanic rocks produces fertile soils for agriculture.

Question 76

Volcanic calderas,which are dozens of kilometres across and produced by very rare,large eruptions are referred to as super volcanoes.

Question 77

Geothermal energy is a renewable resource that cannot be depleted until the volcano goes extinct.

Question 78

Ash fall is a significant health hazard.

Question 79

Lahars are avalanches of hot gas,ash and volcanic rock fragments that flow down slopes during eruptions.

Question 80

Shield volcanoes commonly erupt tephra.